Image adjustment derived from optical imaging measurement data

Abstract

A method and apparatus for imaging within the eye is provided whereby a component of eye position is detected using optical imaging data. Tracking eye position over time and correctly registering imaging data for scan locations or using eye position to detect decentration achieves improved imaging. In one embodiment, essentially perpendicular B-scans are imaged sequentially and the corneal arc within each B-scan is analyzed to determine the vertex of the eye. The eye vertex is tracked over pairs of perpendicular B-scans to determine eye motion. In another embodiment, the decentration in the Pachymetry map is removed by correcting for the misalignment of the center of the Pachymetry map and the actual location of the corneal vertex.

1. A method of generating an image of an eye from measurement data collected using an optical imaging device comprising:
 (a) collecting measurement data along a plurality of scan lines; 
 (b) identifying a structural feature within the eye based on the measurement data; 
 (c) determining a plurality of position parameters associated with the identified structural feature; 
 (d) analyzing the position parameters to determine a location associated with the structural feature, said location corresponding to one of a vertex, a projection of the vertex and geometrical equivalents thereof; 
 (e) adjusting the coordinates of the measurement data based on the determined location; and 
 (f) creating an image using at least a portion of the adjusted measurement data. 
 
   
   
     2. A method as recited in  claim 1 , wherein the location is tracked over time. 
   
   
     3. A method as recited in  claim 1 , wherein at least a portion of the measurement data is rejected due to the determined location exceeding a threshold. 
   
   
     4. A method as recited in  claim 1 , wherein the adjusting step is a spatial correction of the image coordinates. 
   
   
     5. A method as recited in  claim 4 , wherein interpolation is used to improve the image adjustment. 
   
   
     6. A method as recited in  claim 4 , wherein the image is a Pachymetry map, which is adjusted for eye misalignment. 
   
   
     7. A method of deriving a component corresponding to eye position from measurement data collected using an optical imaging device comprising:
 (a) collecting a plurality of B-scans imaging a structural feature; 
 (b) identifying a first point corresponding to an extrema of the feature in a first B-scan; 
 (c) identifying a second point corresponding to an extrema of the feature in a second B-scan; 
 (d) computing a first perpendicular to the first B-scan through the first point; 
 (e) computing a second perpendicular to the second B-scan through the second point; and 
 (f) determining the intersection of the first and second perpendiculars in a projection plane to derive a component corresponding to eye position. 
 
   
   
     8. A method as recited in  claim 7 , wherein steps (a)-(f) are performed two or more times. 
   
   
     9. A method as recited in  claim 8 , wherein successive position components are used to track eye motion. 
   
   
     10. A method as recited in  claim 9 , wherein successive vertex positions are used to correct for misalignment of the Pachymetry map. 
   
   
     11. A method as recited in  claim 7 , wherein the plurality of B-scans are evenly distributed about a center point. 
   
   
     12. A method as recited in  claim 11 , wherein successive B-scans are essentially perpendicular. 
   
   
     13. A method as recited in  claim 12 , wherein there are 8 B-scans. 
   
   
     14. A method as recited in  claim 7 , the component of eye position is the component of the vertex along the scan axis. 
   
   
     15. A method as recited in  claim 7 , wherein the optical imaging device is an optical coherence tomography imaging device. 
   
   
     16. A method as recited in  claim 7 , wherein the structural feature is the anterior surface of the cornea. 
   
   
     17. A method as recited in  claim 7 , wherein the component of eye position is the projection of the vertex. 
   
   
     18. A method of registering biometric map data of the eye using an optical coherence tomography imaging device comprising:
 (a) collecting measurement data along a plurality of scan lines imaging a structural feature; 
 (b) analyzing the measurement data to determine a location associated with the structural feature, said location corresponding to one of a vertex, a projection of the vertex and geometrical equivalents thereof; and 
 (c) registering the biometric map data for the plurality of scan lines as a function of the determined location. 
 
   
   
     19. A method as recited in  claim 18 , wherein the biometric map is a Pachymetry map. 
   
   
     20. A method as recited in  claim 19 , wherein the adjustment corrects for misalignment between a scan pattern generated by the scan lines and the vertex. 
   
   
     21. A method as recited in  claim 18 , wherein the biometric map data is registered to the vertex scan line by scan line. 
   
   
     22. A method as recited in  claim 19 , wherein the registering step utilizes interpolated positions of the vertex. 
   
   
     23. A method as recited in  claim 18 , wherein steps (a)-(c) are performed two or more times. 
   
   
     24. A method as recited in  claim 23 , wherein the registration function is a translation by a constant multiple of the change in vertex position. 
   
   
     25. A method as recited in  claim 24 , wherein the constant multiple is greater than 1. 
   
   
     26. A method as recited in  claim 25 , wherein the biometric map is corrected for eye rotation. 
   
   
     27. An optical coherence apparatus for biometric imaging comprised of:
 (a) a light source for illuminating at least one feature within a sample; 
 (b) a sample optical beam reflected from the sample; 
 (c) a reference optical beam; 
 (d) an interferometer for combining the sample optical beam with the reference optical beam; 
 (e) a detector to detect measurement data from the combined beams; 
 (f) a processor for analyzing the measurement data to determine a location associated with a structural feature within the eye, said location corresponding to one of a vertex, a projection of the vertex and geometrical equivalents thereof; and 
 (g) a display for displaying an image spatially adjusted as a function of the determined location. 
 
   
   
     28. An apparatus as recited in  claim 27 , wherein the optical imaging apparatus is optimized for viewing an anterior surface of the eye. 
   
   
     29. A apparatus as recited in  claim 27 , wherein the optical imaging apparatus is optimized for viewing a posterior surface of the eye.